Flora of the Canadian Arctic Archipelago

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S.G. Aiken, M.J. Dallwitz, L.L. Consaul, C.L. McJannet, R.L. Boles, G.W. Argus, J.M. Gillett, P.J. Scott, R. Elven, M.C. LeBlanc, L.J. Gillespie, A.K. Brysting, H. Solstad, and J.G. Harris

Poa hartzii Gand.

English: Hartz's bluegrass,

French: Pâturin de Hartz,

Inuktitut Iviit, ivisuka, ivitsuskaka.

Poaceae, Grass family.

Published in Bull. Soc. Bot. France 66: 302. 1919.

Type: Greenland: Kordlunguak, 08.1890, leg. N.Hartz. Holotype: P.

Synonymy. Poa hartzii Gand. var. vivipara Polunin, Bull. Natl. Mus. Canada 92 (Biol. Ser. 24): 70. 1940.

Poa glauca Vahl var. atroviolacea Lange f. prolifera Simmons, Vasc. Pl. Fl. Ellesmereland. 163. 1906. Syntypes: Canada. Nunavut: Ellesmere Island, Goose Fjord, at the Yellow Hill Simmons 3587, and Midday Knoll 3500, 3643 (GH!).

Poa hartzii Gand f. prolifera (Simmons) B. Boivin.

Vegetative morphology. Plants 10–33 cm high; perennial herbs; caespitose (shoots extravaginal and intravaginal). Only fibrous roots present. Ground level or underground stems absent (or rarely appearing somewhat rhizomatous in very loose soil). Aerial stems erect. Leaves mainly basal; alternate; marcescent. Prophylls 5–10 mm long; with smooth veins; with pronounced keels, or lacking pronounced keels. Petioles absent. Sheaths present; with the margins fused only in the lower part; glabrous; sheath collars present. Ligules present; (1.8–)2.4–4(–5) mm long; membranous; glabrous; lanceolate, or ovate-oblong. Ligule apices acuminate, or acute (narrowly); entire, or erose. Leaves grass-like. Blades 20–130 mm long, 0.5–1.2 mm wide (folded width), appressed to the stem or spreading, folded in bud, linear, flat (rarely) or folded, veins parallel, midvein similar in size to other veins in the leaf, bulliform cells in distinct rows on either side of the midvein. Blade adaxial surface glabrous. Blade abaxial surface glabrous.

Reproductive morphology. Flowering stems two or more per plant. Flowering stems circular or oval in cross section. Flowering stems with leaves; culm nodes not exposed (usually), or becoming exposed (rarely); culm nodes number visible 0–1. Inflorescences paniculate; dense; linear, or lanceolate, or pyramidal; 2.5–6 cm long; 5–20 mm wide (pancile narrow, about three times as long as wide). Inflorescences main axis glabrous (sometimes scabrous). Number of inflorescence branches at lowest node 2 (usually). Inflorescence primary branches 6.5–12 mm long; glabrous, or scabrous (sparsely so); with appressed secondary branches. Spikelets disarticulating above the glumes; ovate; 4.8–7.4 mm long; 1.7–3.3 mm wide. Florets per spikelet 3–4(–6). Two glumes present. First glume 0.76–0.97 × the length of the second glume; 0.41–0.66 × spikelet length; 2–4 mm long; lanceolate; glabrous; margins glabrous; veins 1(–2); apex acute. Second glume 0.4–0.9 × as long as the spikelet; almost as long as, or longer than, the lowest floret (or barely as long); 2.2–4.2 mm long. Second glume lanceolate. Second glume glabrous; veins 3. Rachilla not pronounced between the florets; extending beyond the uppermost floret; internode 0.9–1.2 mm long; internode glabrous. Callus differentiated (villous crown around the callus); hairs (0.5–)0.8–2 mm long; hairs shorter than the floret. Lemma ovate; (3.3–)3.9–5 mm long; keeled (weakly), or rounded on the back; surface dull (apical margins thinner than the body of the lemma); surface hairy; surface with trichomes on and between the veins (base sparsely lanate, hairy on and between the veins in the lower half, with longer hairs towards the base); veins 5; apex acute; apex entire; awnless. Palea well developed; 2.3–4 mm long; veins hairy. Flowers bilaterally symmetrical (zygomorphic). Perianth represented by lodicules. Sepals modified (but not a pappus). Stamens 3. Anthers splitting longitudinally. Anthers 0.6–2 mm long (often transparent or shrunken). Ovary superior; carpels 3; syncarpous. Ovaries glabrous. Styles 2. Placentation basal. Ovules per ovary 1. Fruit sessile; dry; a caryopsis; indehiscent. Seeds 1.

Chromosome information. 2n = 63–70 (Tzvelev 1976; no Canadian counts known in 2003).

2n (9–10x) = 63-70. Holmen (1952, Greenland, 2n = 63–70, 'corrected' to 2n = about 70 by Löve and Löve 1975); Sokolovskaya (1955, listed after Löve and Löve 1975, but not entered as such by Bolkhovskikh et al. 1969); Jørgensen et al. (1958, Greenland); Petrovsky and Zhukova (1981, Wrangel Island).

Ploidy levels recorded 9x-10x.

Taxon as an environmental indicator. This species is an earlier coloniser of High Arctic calcareous sandy or gravelly substrates. Plants grow usually as isolated tussocks sometimes in association with Poa abbreviata and Puccinellia angustata.

Ecology and habitat. Substrates: slopes; sand, clay; calcareous. Found on alluvial clay, dry, sandy gravel, on hillsides, or floodplains, and around animal burrows. It appears to be limited to calcareous soils.

North American distribution. Northwest Territories Islands, continental Northwest Territories. Range in the Canadian Arctic Archipelago moderate (to widespread). Common. Arctic. Arctic islands: Baffin, Ellesmere, Axel Heiberg, Banks, Victoria.

Northern hemisphere distribution. Amphi-Atlantic, or amphi-Beringian (?), or North American. Svalbard – Franz Joseph Land, Wrangel Island (?), Central Canada, Labrador – Hudson Bay, Ellesmere Land – Peary Land, West Greenland, East Greenland.

General notes. Field observations, morphological evidence, and germination trials reported in Gillespie et al. (1997) support P. hartzii as a morphologically distinct apomictic species that reproduces by seed. DNA evidence in the same paper provides evidence for two possible origins of P. hartzii. The first is a hybrid origin between two ancestral species. The second, and more likely, is that P. hartzii was an existing species that "captured" DNA from a second species, P. glauca (Gillespie et al. 1997). Recent molecular evidence supports the second hypothesis, since P. hartzii has a unique cpDNA haplotype within the P. sect. Secundae group (Gillespie and Boles 2001, Gillespie and Soreng 2005). Individuals of P. hartzii, having a haplotype identical to that of P. glauca (widespread in Arctic Canada), were found only in High Arctic sites and are postulated to result from hybridisation and introgression.

Poa hartzii was previously thought to be possibly P. abbreviata or P. arctica × P. glauca. Cayouette (1984) recorded a collection of P. hartzii from northern Quebec and summarised the debate concerning this taxon, pointing out that Sørensen (1953), Holmen (1957), and Porsild (1964) considered it a species. According to Sørensen (1933), "Even if Poa Hartzii is thus intermediate in many respects between P. abbreviata and P. glauca, it hardly represents the hybrid between these two species". Jørgensen et al. (1958) noted that individuals of P. hartzii in Greenland showed meiotic irregularities and formed abnormal pollen but developed good seeds that lead them to conclude that the taxon was apomictic. Scholander (1934) observed P. hartzii to be intermediate between P. abbreviata and P. glauca, whereas Nannfeldt (1935) suggested that it may be the hybrid P. arctica × P. abbreviata. Edmondson (1980) treated it as a stabilised, but apparently sterile, hybrid of P. abbreviata × P. glauca. Soreng (1991) discussed P. hartzii as a species that possibly had a hybrid origin.

In Svalbard, this taxon sometimes forms stands over large areas (tens of kilometres) with well-defined individuals (1000–10000, at least), where it is obviously seed-propagated, even though it flowers late. It appears to be agamospermic, as no evidence of fertile pollen has been found, agreeing with the North American findings given above (R. Elven, personal communication, 1999).

Haugen (2000) investigated possible hybrid origins of Poa hartzii and P. arctica subsp. caespitans in Svalbard, using morphological and isozyme techniques. In the populations studied she found P. hartzii was enzymatically non-varying and had a unique multilocus phenotype and most similar to P. glauca.

Illustrations. • Close-up of plant. Cespitose or tufted plant with purplish, paniculate, short-branched inflorescences. Nunavut, Axel Heiberg Island. 4 August, 1999. L.J. Gillespie 6623, L.L. Consaul and R.J. Soreng. CAN. • Close-up of plant. Tufted plant with short purplish panicles with vegetatively proliferating spikelets. Nunavut, Axel Heiberg Island, Nansen Sound. 4 August, 1999. L.J. Gillespie 6623, L.L. Consaul and R.J. Soreng. CAN. • Close-up of inflorescence. Vegetatively proliferating spikelets with brownish glumes and an elongated first lemma. Nunavut, Axel Heiberg Island, Nansen Sound. 4 August, 1999. L.J. Gillespie 6623, L.L. Consaul and R.J. Soreng. CAN. • Three grasses at Eureka. Three grasses growing close together on clay substrate near a stream. Poa hartzii (near knife), Poa abbreviata (right, top) and Puccinellia angustata (right, bottom). Nunavut, Ellesmere Island, Eureka weather station. August, 1991. • Type specimen. Syntype of Poa glauca Vahl var. atroviolacea Lange f. prolifera Simm., annotated as Poa hartzii f. prolifera. Nunavut, Ellesmere Island, Goose Fjord, 1901, Herman G. Simmons 3643. (Syntype: GH). Label reads: "In sinu Goose Fjord Ellesmere- landiae meridionalis in campsis ?agitraccis at ?Mirray Knoll. 36.VIII.1907. leg. et determ. Herman G. Simmons.". • Arctic Island Distribution.


This publication is available on the internet (posted May 2011) and on CD-ROM (published in 2007). These versions are identical in content, except that the errata page for CD-ROM is accessible on the main index page of the web version.

Recommended citation for the web-based version of this publication: Aiken, S.G., Dallwitz, M.J., Consaul, L.L., McJannet, C.L., Boles, R.L., Argus, G.W., Gillett, J.M., Scott, P.J., Elven, R., LeBlanc, M.C., Gillespie, L.J., Brysting, A.K., Solstad, H., and Harris, J.G. 2007. Flora of the Canadian Arctic Archipelago: Descriptions, Illustrations, Identification, and Information Retrieval. NRC Research Press, National Research Council of Canada, Ottawa. http://nature.ca/aaflora/data, accessed on DATE.

Recommended citation for the CD-ROM version of this publication: Aiken, S.G., Dallwitz, M.J., Consaul, L.L., McJannet, C.L., Boles, R.L., Argus, G.W., Gillett, J.M., Scott, P.J., Elven, R., LeBlanc, M.C., Gillespie, L.J., Brysting, A.K., Solstad, H., and Harris, J.G. 2007. Flora of the Canadian Arctic Archipelago: Descriptions, Illustrations, Identification, and Information Retrieval. [CD-ROM] NRC Research Press, National Research Council of Canada, Ottawa.

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